Field of the Invention
The invention relates to a method for optimizing a magnetic resonance sequence for operating a magnetic resonance apparatus, a method for operating a magnetic resonance apparatus, a sequence optimizing device, a magnetic resonance apparatus and a storage medium encoded with programming instructions that cause a computer to implement such a method.
Description of the Prior Art
In a magnetic resonance apparatus, also known as a magnetic resonance tomography system, the body of the subject to be examined, particularly that of a patient, is typically exposed to a relatively strong magnetic field of, for example, 1.5 or 3 or 7 Tesla, with the use of a basic field magnet of a scanner in which the subject is situated. In addition, gradient switching sequences are activated by a gradient coil arrangement of the scanner. By operation of a radio frequency antenna in the scanner, using suitable antenna devices, radio frequency pulses, particularly excitation pulses, are radiated, which cause nuclear spins of particular atoms excited into resonance by these radio frequency pulses to be tilted through a defined flip angle relative to the magnetic field lines of the basic magnetic field. Upon relaxation of the nuclear spin, radio frequency signals known as magnetic resonance signals are emitted and are received by suitable radio frequency antennae, and are then further processed. From the raw data thereby acquired, the desired image data can ultimately be reconstructed.
For a particular scan, therefore, the scanner is operated according to a specific magnetic resonance sequence, also known as a “pulse sequence,” formed as a sequence of radio frequency pulses, in particular excitation pulses and refocusing pulses, as well as gradient switching sequences to be activated, coordinated in time with the radio frequency pulses, on various gradient axes along different spatial directions. Temporally adapted thereto, readout windows are set that specify the time frames within which the induced magnetic resonance signals are detected.
The gradient switching sequences specified by the magnetic resonance sequence can lead to the magnetic resonance scanner having a high level of loudness during the acquisition of the magnetic resonance data.